The Seven Most Massive Clumps in W43-Main as Seen by ALMA: Dynamical Equilibrium and Magnetic Fields

Here we present new ALMA observations of polarized dust emission from six of the most massive clumps in W43-Main. The clumps MM2, MM3, MM4, MM6, MM7, and MM8, have been resolved into two populations of fragmented filaments. From these two populations we extracted 81 cores (96 with the MM1 cores) with masses between 0.9 M _o˙ to 425 M _o˙ and a mass sensitivity of 0.08 M _o˙. The MM6, MM7, and MM8 clumps show significant fragmentation, but the polarized intensity appears to be sparse and compact. The MM2, MM3, and MM4 population shows less fragmentation, but with a single protostellar core dominating the emission at each clump. Also, the polarized intensity is more extended and significantly stronger in this population. From the polarized emission, we derived detailed magnetic field patterns throughout the filaments that we used to estimate field strengths for four out of the six clumps. The average field strength estimates were found to lie between 500 μG to 1.8 mG. Additionally, we detected and modeled infalling motions toward MM2 and MM3 from single-dish HCO⁺(J=4 → 3) and HCN (J=4 → 3) data, resulting in mass infall rates of M_MM2 =1.2 × 10^-2 M _o˙ yr^-1 and M_MM3 =6.3&times 10^-3 M _o˙ yr^-1. Using our estimations, we evaluated the dynamical equilibrium of our cores by computing the total virial parameter α _total. For the cores with reliable field estimates, we found that 71% appear to be gravitationally bound while the remaining 29% are not. We conclude that these unbound cores, which are also less massive, are still accreting and have not yet reached a critical mass. This also implies different evolutionary timescales, which essentially suggests that star formation in high-mass filaments is not uniform.